1. Field of the Invention
This invention relates to a method for controlling opening/closing of a door in an automatic door system.
2. Description of the Prior Art
In general, automatic door systems are arranged such that a belt is wound round a drive pulley driven by an electric motor and a driven pulley, the belt being connected to a door, and when the motor is driven or rotated forwardly or reversely the belt is turned forwardly or reversely so as to move the door either in opening direction or in closing direction.
As such method for controlling opening/closing of a door in an automatic door system, a variety of methods have been developed.
For example, there is a method for controlling opening/closing of a door in an automatic door system as described in Japanese Laid-Open Patent Application No. Sho63-66991, wherein the door is caused to conduct an opening operation so as to move it to its opening-stop point after a power supply switch is turned on; storing in a memory counter the pulses generated during the opening operation by a rotation detector adapted to generate pulses whose count is proportional to the number of revolutions of the motor; subsequently causing the door to conduct a closing operation and also counting the pulses generated by the rotation detector during the closing operation by means of a counter; and stopping the motor when the count of the pulses corresponds to the count stored in the memory counter.
According to such a method of controlling opening/closing of a door in an automatic door system, since the distance of movement of the door is stored in a storage device by causing it to conduct an opening operation when a power supply switch is turned on, and during the subsequent closing operation or opening operation of the door the control of operations of the door is conducted on the basis of the stored distance of movement of the door, opening/closing operation of the door can be conducted without any overrun.
However, in the above-mentioned method for controlling opening/closing of a door in an automatic door system, since the distance of movement of the door is measured on the basis of the number of revolutions of the motor, if the belt is slipping, there is a possibility that the distance of movement of the door measured on the basis of the number of revolutions of the motor does not correspond to the actual distance of movement thereof, thus causing an overrun.
Further, in case the door is caused to conduct opening/closing operations, the door is moved at a high speed to a predetermined position and then decelerated by applying brake to the motor to decelerate the same so as to move the door a low speed either to its opening-stop point or to closing-stop point, and also control of opening/closing of the door is made by comparing the initial acceleration and the deceleration upon braking thereof with their respective preset values. Therefore, if the initial acceleration and the deceleration upon braking of the door differ from their respective preset values, there is a possibility of the acceleration distance and the deceleration distance of the door varying thus rendering it impossible to move the door smoothly. Stating in brief, in case the resistance to sliding door increases excessively due to abnormal conditions of the reduction gear, the door-roller and the rails, etc., or in case the acceleration force or the braking force is reduced due to abnormal conditions of the motor driving circuit, the acceleration distance and the deceleration distance will differ extremely from their respective preset values thus endangering persons who pass through it and rendering it unable to control opening and closing of the door.